This invention relates generally to the field of preparing antioxidants from naturally occurring plant materials, i.e, Rosmarinus officinalis ("rosemary") and Salvia officinalis ("sage"). The process of this invention produces carnosic acid (See FIG. 1) of high purity.
Antioxidants serve in a number of important commercial applications, especially as ingredients in food products susceptible to degeneration, in one form or another, due to oxidation. "Antioxidants" are defined by the Food and Drug Administration (21 CFR .sctn. 170.3) as "substances used to preserve food by retarding deterioration, rancidity, or discoloration due to oxidation." Commercial applications include use in processed meat and poultry, salad dressings, seasonings, snacks, nuts, soup bases, edible fats and oils, natural foods, pet foods and packaging. In addition to foods, antioxidants have been used to prevent oxidation in various cosmetic and toiletry products and in medicinal or pharmaceutical preparations. The primary purpose in each of these applications is to prevent deterioration of desirable product characteristics by inhibiting oxidation.
More recently, antioxidants in food sources and dietary supplements have received attention for their potential to prevent or delay the onset of certain cancers and other chronic health conditions including heart disease, cataracts and aging. The theory is that, by preventing oxidation, these materials inhibit the formation of oxygen containing free radicals that are believed to play a significant role in initiation of these conditions and other chronic disorders.
The use of spices to prevent food deterioration as well as to impart flavor has been known for centuries. Because of their cost and availability, however, synthetic antioxidants, such as butyl hydroxyanisole ("BHA") and butylated hydroxytoluene ("BHT"), have been predominant in commercial food preparation. These antioxidants have proven quite effective. However, significant questions have been raised about their safety. For example, BHA has been identified as a "carcinogen" by the International Agency for Research on Cancer and has been banned in Europe. The safety of BHT has also been questioned.
Because of these concerns, there has been an increasing interest in the use of naturally occurring antioxidants in food preparation. These include various phenolic diterpenes, such as carnosic acid which is found in and can be isolated from certain spices, particularly rosemary and sage. Recent tests indicate that carnosic acid is significantly more effective than other naturally occurring antioxidants, as well as certain synthetic antioxidants, such as BHA and BHT. Antioxidants prepared from rosemary or sage extracts have certain additional advantages including the fact that they are stable at high temperatures compared to other antioxidants. As a result carnosic acid has a greater "carry-through" in commercial food preparation processes. In addition, carnosic acid is readily soluble in oil. Apart from its superior characteristics as an antioxidant, many consumers perceive that naturally occurring antioxidants, such as carnosic acid, are inherently safer than synthetic "preservatives."
Unfortunately, antioxidants extracted from naturally occurring materials also exhibit flavors, odors and colors that are undesirable in many applications. Accordingly, significant efforts have been expended to find commercially acceptable ways to extract antioxidants from these plant sources and to separate them from other naturally occurring compounds that give rise to these undesirable characteristics. Many processes have been tried, but suffer from various defects, such as cost, lack of selectivity in isolating the antioxidant, or poor yield.